Answer: Imperialism
Explanation: European expansion into the western world was the biggest factor in them becoming involved into world war I.
The Franz Ferdinand assassination<span> was </span>not<span> the </span>cause<span> of war. Tensions between the Great Powers of Europe had been rising gradually since the beginning of the 20</span>th<span> century </span>and<span> it </span>is<span> entirely feasible that a Great War would have taken place had the Archduke </span>not<span> been murdered.</span>